Conventionally, touch panel is mainly used in mobile phones, tablet PCs and some other electronic devices having small-size screens. In recent years, all-in-one PCs, notebook computers and some other electronic devices having large-size screens are also provided with the touch panel. With the increase of screen size, the amount of data to be processed during operation of the touch panel is correspondingly increased. As a result, large-size touch panels should satisfy higher requirements regarding the resistance of the sensing pattern formed on the touch panel, wherein the sensing pattern typically includes a plurality of electrodes and a plurality of lead lines connected with the electrodes. When the touch panel is larger than 14 inches, the existing transparent conductive materials for the electrodes such as ITO (indium tin oxide) are no longer suitable for the large-size touch panel since a resistance value of ITO is relatively large. Thus, the touch panel of new generation is proposed to adopt a mesh structure as the sensing pattern.
FIG. 1 schematically and partially shows the sensing pattern of a touch panel according to the related art. Referring to FIG. 1, taking the sensing pattern being formed in a single layer on the touch panel as an example, the sensing pattern 10 of the touch panel includes sensing electrodes 11, driving electrodes 12, and lead lines 13. The sensing electrodes 11 and the driving electrodes 12 are generally E-shaped and mutually inserted with each other to thereby form the sensing pattern 10. The sensing electrodes 11, the driving electrodes 12 and the lead lines 13 are each formed in a mesh structure 14. That is, the sensing electrodes 11, the driving electrodes 12 and the lead lines 13 are each in the form of mesh structure.
The touch panel has an active region R1 and a peripheral region R2 on at least one side of the active region R1, wherein the electrodes 11, 12 are located in the active region R1 and the lead lines 13 are located in the peripheral region R2. The electrodes 11, 12 serve to generate a signal when the touch panel is touched by a user, so that the touched coordinates can be recognized by a touch controller (not shown). The signal generated from the electrodes 11, 12 is transmitted to the touch controller through the lead lines 13. The lead lines 13 are electrically connected to the electrodes 11, 12 and serve to transmit the signal generated from the electrodes 11, 12 to the touch controller. As for each lead line 13, one end thereof may be connected to at least one of the electrodes 11, 12, and the other end thereof may be electrically connected to a flexible printed circuit board (FPCB) which may be thereafter electrically connected to the touch controller.
The mesh structure 14 includes a plurality of conductive wires 141 intersecting with each other to form a plurality of grids 142 and a plurality of nodes 143 connected between the grids 142. The grids 142 are formed by the conductive wires 141 intersecting with each other, and the nodes 143 are formed at the intersection points of the conductive wires 141. The shape of the grids 142 may be rhombus.
FIG. 2 is an enlarged schematic view showing a portion of the mesh structure 14 of the sensing pattern 10 of FIG. 1. Referring to FIG. 2, since the node 143 is formed at the intersection point of two conductive wires 141, the surface resistance at the node 143 will be larger than the surface resistance of each conductive wire 141, leading to signal attenuation caused by the surface resistance being mainly generated at the nodes 143 as the signal is transmitted by the electrodes 11, 12 and the lead lines 13. The surface resistance at the nodes 143 is relatively large, thus affecting transmission of the signal. Also, the nodes 143 restrict the line width design of the mesh structure. The line width of the conductive wires 141 of the mesh structure cannot be designed too small.